Hang in there Cody,
You have received a lot of good advice that cautions you starting a new business. Your business experience is non-existent, your financial resources are very limited and the marketplace for a storefront hobby shop is poor right now.
The good news, you got heart and it involves trains. There is a place for you, and it is possible you will get some ideas on from the guys on this forum.
Lots of items and services that support this hobby can be made or performed with small overhead at home; I believe the term is cottage industry. Today I was looking at 20 scale Pacemaker boxcars I own and thinking "I wonder where I could find someone to weather these for me". I would encourage you to think micro vs macro. Find some service you enjoy and research, practice then hang out your shingle. Maybe make parts or assemble structures.
Off the top of my head, I don't have any great suggestions, but I bet some of the others on the forum do. Remember if you love what you're doing you will do a good job and you sure seem to enjoy this stuff. So again, hang in there just think smaller to start.
k
